Cu(II), Ni(II), Co(II), Zn(II), and Pd(II) Complexes with (4Z)-4-[(2-Furylmethylamino)methylene]-5-methyl-2-phenylpyrazol-3-one: Synthesis, Structures, and Properties

(4Z)-4-[(2-Furylmethylamino)methylene]-5-methyl-2-phenylpyrazol-3-one (HL) and its Cu(II), Ni(II), Co(II), Zn(II), and Pd(II) complexes with the ML2 composition are synthesized. The structures of the complexes are studied by elemental C,H,N analysis, IR spectroscopy, magnetochemical measurements, and quantum chemistry. The crystal structures of the copper(II) and cobalt(II) complexes are determined by X-ray diffraction (XRD) (CIF files CCDC nos. 2177619 and 2177622, respectively). Two deprotonated ligands are coordinated to the metal ions via the chelate mode by the nitrogen atom of the imino group and the oxygen atom of the hydroxy group of the ligand. The geometry of the copper(II) ion environment corresponds to a distorted planar square, whereas the cobalt(II) ion exists in a distorted tetrahedral environment. In the series of the compounds studied, fluorescence with a maximum at 431 nm and a quantum yield of 0.29 is observed for the Zn(II) complex in a solution of CH2Cl2. The synthesized enamine and metal complexes are tested for antibacterial, protistocidal, and fungistatic activities. All compounds are shown to have no fungistatic and antibacterial activities, and only a weak protistocidal activity is found for the copper and zinc complexes.